Endometriosis is a painful disorder that is characterized by the ectopic implantation of functioning endometrial tissue into the abdominal wall and the outer surface of various organs including, most commonly, the lower bowel, ovaries and fallopian tubes. P. Vigano et al. (1991) Fertility and Sterility 56:894. Currently, endometriosis-specific genes have not been identified and the events relating to the development of endometriosis are poorly understood. However, several reports suggest that retrograde menstruation linked with abnormal immune function may play a role in establishing ectopic endometrium lesions. T. Ishimaru and H. Masuzaki (1991) Am. J. Obstet. Gynecol. 165:210-214. Many attempts to isolate antigens from ectopic endometrium lesions have failed, due to the necrotic nature of the lesions.
Endometriosis also is recognized has having an autoimmune component. IgG and IgA auto-antibodies that react with multiple endometrial antigens have been documented in patients with endometriosis. However, attempts to develop IgG or IgA-based assays for the diagnosis of endometriosis has fallen short of fruition. S. Fernandez-Shaw et al., (1996) Hum. Reprod. 11:180-1184. R. A. Wild et al. (1991) Obstetrics and Gynecology 77:927. Studies have shown that circulating IgG antibodies that bind multiple endometrial proteins can be detected in women with endometriosis to varying degrees. Thirty-five percent to 74% of patients have sera reactive with endometrial proteins. O. Odukoya et al. (1996) Acta Obstet. Gynecol. Scand. 75:927-931; J. G. Kim et al. (1995) Am. J. Reprod. Immunol. 34:80-87; O. A. Odukoya et al. (1995) Hum. Reprod. 10:1214-1219. It has also been shown that endometrial antibody titers in patients that respond well to danazol are significantly lower ( 7/18 (39%) treated patients had elevated titers) than those patients with untreated endometriosis or patients that responded poorly to treatment ( 17/23 (74%) untreated patients had elevated titers). A. El-Roeiy et al. (1988) Fertility and Sterility 50:864-871; H. J. Chihal et al. (1986) Fertility and Sterility 46:408-411. In addition, it has been recently reported that women with endometriosis have elevated levels of IL-4, a Th2 mediating cytokine, and that treatment with danazol reduces the levels of IL-4 in women that respond well to treatment. C.-C. Hsu et al. (1997) Fertility and Sterility 67:1059-1064.